Circuit breaker



Aug. 7, 1945. H. LANGSTROTH 2,381,294 V CIRCUIT BREAKER Filed April 13,1945 s Sheets-Sheet 1 :3 k Inveniar HALL LANGSTROTH Aug. 7, 1945. H.LANGSTROTH 2,381,294

CIRCUIT BREAKER Filed April 13, 1943 3 Sheets-Sheet Jizven?0r- HALLLANGSTROTH tion.

' Patented Aug. 7, 1945 2,381,294 CIRCUIT BREAKER nan Langstroth,Greenwich, Conn., ass 'or to Maguire Industries, Incorporated, acorporation or New York Application April 1a, 1943, Serial No. 482,848

10 Claims. (01.200-116) My invention relates to a circuit breaker, andmore particularly to a small circuit breaker having manually operatedreset and release mechanism,-together with automatically operatedrelease mechanism. The invention isparticularly useful in itsapplication to automotive units, es-

pecially .airplanes, to which use, however, it isv not restricted.

One object of the invention is to provide a small, compact circuitbreaker hich may be conveniently mounted at points w h ere little spaceis available. Another object is the provision of such a circuit breakerwhich may be operated to break the circuit either by an overload orconveniently by hand, and which may be reset by hand with equal ease andconvenience. Still another object is the provision of a mounting for amovable contact in such form that relative movement may be effectedbetween the mountin and the contact without pivoted r sliding parts. Afurtherv object is the provision of such a small,

compact circuit breaker which may be held in' circuit closing positionby hand. Still a further object is the provision of such a circuitbreaker wherein the operating handle has but two positions, whereby itwill be obvious at aglance whether the contacts are in open or closedposi- Other objects of the invention will be apparent upon considerationof the present speciflcation.

One form of the invention accompanying drawings, in which- Figure 1 isan elevation of a circuit breaker constructed in accordance with theinvention,

one part of the casing being removed to show the mechanism, and theelements being shown in circuit closing position,

Fig. 2 is a view similar to Figure 1, showing the elements in opencircuit position,

Fig. 3 shows the circuit breaker as seen from below, the casing beingassembled andthe handle being shown,

Fig. 4 is an elevation similar to Figure 1, the operating elements 01the circuit breaker being removed irom the casing,

Fig. 5 is a cross section taken on the line V-V. of Fig. 7, the elementsbeing shown a in circuit closing position,

Fig. 6 is a fragmental view similar to Figure 1, the elements beingshown at the moment the circuit breaker is tripped by hand, g

Fig. 7 is a horizontal mid-section of the circuit breaker taken on theline VII-VII of Figure 1,

is illustrated in. the

Fig. 8 is a vertical section taken on the line VIIIVIII of Figure 1,Fig. 9 shows the interior of the casing with all operating elementsremoved, as viewed on the line'IXIX of Fig. 8,

Fig. 10 is a vertical mid-section taken on the lineX-X of Fig. 9, and

Fig. 11 is a horizontal mid-section taken on the line XI-XI of Fig. 9.

An important problem in designing a circuit breaker is that of providinga breaker in such sturdy form that it may be used with confidence for avariety of purposes when made in a variety of sizes. Another importantproblem is that of providing such a breaker which may be tripped withminimum force to give a quick break, and which will maintain fullcontact pressure up to the time of breaking. I have found that suchresults may be obtained if butt engagement is made between the contacts,under pressure, and if substantially frictionless multiplication of theresetting or tripping force is efiected, which is advantageous in asmall breaker.

The particular embodiment of the invention illustrated in the drawingsshows a two part casing 20 in which all of the operating parts areinclosed. Thus, the entire assembly may be fitted together in acontainingpart 2| of the easing with'only certain elements projectingtherefrom. A cover 22, complementary to the containing part 2|,completes the casing, and provides an opening 22a and sockets 22b and22cto accommodate certain parts, as will be subsequently explained.

A stationary contact 23 is fixed in a recess 24 in the containing part2| of the casing, and is connected by a lead 25 to a terminal 26 outsideof the casing. As here shown, the lead 25 and the terminal 26 areunitary, but such is not necessarily the case.

A movable contact 21 is also contained within the casing 20, and when inclosed circuit position, meets the fixed contact 23 m butt engagementwhere it is held in position under pressure.

resilient metal arm II, the other end of which is The movable contact 21is carried by a support, herebent to form an angle 32 which is firmlyheld in a recess formed in the support; or rotor 28. In consequence ofthis arrangement, when the rotor 28 is turned in contraclockwisedirection, as viewed in Figs. 1 and 2, face-to-face meeting or buttengagement is made between the contact 23 and 21. If the rotor 28 isturned through a greater angular distance than the contact 21, then byreason of the flexibility or resilience of the arm 3|, engagement of thecontacts is made under pressure. Thus relative movement is possiblebetween the movable contact 21 and the rotor 28 without the use ofpivoted or sliding connection between the movable contact and the rotor.

Means is provided for normally urging the rotor in a clockwise directionas viewed in Figs. 1 and 2: that is to say, into open circuit position.In the embodiment here shown this means comprises a tension spring 33'housed in an arc-shaped channel 34 in the rotor 28. One end of thespring 33 is attached to the rotor adjacent the angle 32. The other endof the Spring is attached to a post 35 fixed to the containing pa'rt 2|of the casing 20. Thus the spring 33 always tends to move the rotor intoopen circuit position, as illustrated in Fig. 2.

Releasable means is also provided for holding the movable contact incircuit closing position. As shown in the drawings this means comprisesa bi-metal strip 33 fastened at one end in the containing part 2| of thecasing as by a screw 31. This bi-metal strip curves around the rotor andits free end 38 extends beyond the angle 32 formed on the arm 3|, in allpositions of the rotor.

iii

A leaf spring 39 is fixed to the inside of the curved I bi-metal strip36 in a position to engage an end 40 oi. the arm 3| which projectsbeyond the rotor from the point 32 at which the arm 3| is attached tothe rotor. Thus, as the rotor is turned to bring the contacts intocircuit closing position, the end 40 rides over the leaf spring 39bowing the resilient bi-metal strip 36 slightly away from the rotor.After the contacts 23 and 21 have been closed. the rotor continues toturn until the end 43 passes beyond the spring 39, whereupon theresiliency of the bi-metal strip 36 brings the spring 33 up behind theend 40 to hold the rotor in circuit closing position. (See Figure 1.)

The circuit passes through the bi-metal strip 38 from a terminal 4|outside ofthe casing, through a lead 42 which passes into the containingpart 2| of the casing and is connected to the bi-metal strip 33 at thescrew 31. A pigtail 43 is attached at one end to the bi-metal strip,preferably adjacent the leaf spring 33, as shown in the drawings, and isalso attached at the other end to the resilient metal arm 3| near theangle 32. As shown in Figs. 1, 2, 5 and 6, a screw 44 attaches thepigtail 43 to the arm 3|, and at the same time attaches the arm 3| tothe rotor 23. Obviously other means might be employed for this purpose.

Operation of the apparatus as so far described is as follows: With theelements in the position shown in Figure 1, current'passes from theterminal 4|, through the lead 42 to the iii-metal strip 33, thencethrough the pigtai143 to the arm 3| to the contact 21-, to the'contact23, the lead 23 and the terminal '23.

The iii-metal strip 33 is so constructed that the rotor will be held inthe position illustrated in Figure 1, against the action 0! the spring33, for all ordinary loads. An overload upon the circuit, however, willtend to straighten the bi-metal strip, according to well-knownprinciples the metal having the greater coefilcient of expansion beingpositioned on the inside of the bi-metal strip. As this straighteningoccurs, the leaf spring 39 will be moved out of engagement with the end43, whereupon the spring 33 will snap the rotor into open circuitposition.

Means is provided for adjusting the action of the bi-metal strip 36. Inthe embodiment illus trated a set screw 45 is disposed in a channel 43in the containing part 2| of the casing 23, and is threaded through thelead 42 to bear against the outer face of the bi-metal strip 36.Accordingly the circuit may pass from the lead 42 to the bimetal strip36 through the set screw 45 thereby shortening the length of thebi-metal strip subject to overload heat. Furthermore, the distance ofthe bi-metal strip from the rotor may be affected by pressure of the setscrew 45. Finally, distortion of the bi-metal strip will be efiectedbeyond the point of contact with the set screw instead of beyond thescrew 31, when pressure is applied to the bi-metal strip by the setscrew. Thus a simple and effective means of calibration is provided.

The invention also contemplates manually operable means for releasingthe releasable means, as well as for moving the contacts into circuitclosing position and for holding them there In the illustrativeembodiment shown in the drawings, there is employed a lever 41 ofinsulating material pivoted in the socket 220 by means of a nipple 48formed thereon, and resting on its opposite side against the rotor 28and the containing part 2|, all as best shown in Fig. 7. The lever 41has a handle 43 formed thereon which extends through the opening 22aoutside of the casing. The lever is cut away, as at 50, so that it mayoperate in all positions without interference with the pivot or stemupon which the rotor 28 turns.

A cam surface 5| is formed upon the lever 41 on the opposite end thereoffrom the handle 43. This cam surface coacts with a roller 52 pivotallymounted upon the rotor 23 to turn the rotor into circuit closingposition as the handle is moved from the position shown in Fig. 2 tothat shown in Figure 1. The cam surface and roller contact makes itpossible to close the circuit by means of the lever 41 substantiallywithout friction.

A projection 53 is formed on the lever 41 in a. position to engage thefree end 33 of the bi-metal strip 36 and move the bi-metal strip awayfrom the rotor. Thus, by moving the handle 43 from the position shown inFigure 1 to that shown in Fig. 2, the rotor may be released by hand, andthe contacts brought into open circuit position through the action ofthe rotor spring 33. Fig. 8 shows the elements at the instant oftripping by means of the lever 41. If the breaker is tripped by anoverload which distorts the bi-metal strip 36 and thereby disengages theleaf spring 33 from the end 43, the roller 32 acting against the camsurface 3| turns the lever into the position shown in Fig. 2. Whetherthe circuit is broken by hand orby overload, the projection 33 engagesthe end 33, as shown in Fig. 2, and holds the bi-metal strip 36 awayfrom the rotor 23. The circuit breaker cannot then be reset in closedcircuit 56 formed in the depression concentric with the nipple 48. Oneend of the spring 54 is turned at a right angle and positioned in a hole51 in the lever 41. The other end of the spring is turned in theopposite direction and positioned in a hole 58 in the cover 22. Theforce exerted by the spring tends to keep the lever in circuit closingposition. However, this force is insufiicient to overcome the force ofthe rotor spring 33, and merely prevents displacement of the lever byvibration or unintentional slight force upon the handle.

As the rotor is moved from open circuit position to closed circuitposition the contact 21 is held momentarily by a hump 59 extending fromthe interior wall of the containing part 2| into its path. As the handle49 continues to move toward closed circuit position, tension on theresilient arm 3| is increased until the movable contact 2'! snaps overthe hump and makes quick contact. Movement in the'opposite direction, toopen the circuit, is effected very quickly by the tension of the rotorspring 33, as engagement of the end 40 by the leaf spring 39 isreleased. The contacts are opened instantly, and the hump 59 does notappreciably retard the movable contact 21 in reaching full open circuitposition. The hump 59 may, of course, be given a variety of forms. It ishere illustrated rather diagrammatically because difierent operatingrequirements may call for different hump contours.

In order to prevent the rotor 28 from exceeding the desired angulartravel a unitary segmental boss 60 is formed on its face farthest fromthe lever 41. A fan shaped trough 6| is formed in the inner surface ofthe containing part 2| to accommodate the segmental boss when the rotoris in place. The angular length of the trough is equal to the angularlength of the boss 60 plus the angular distance which the rotor travelsfrom open circuit to closed circuit position. The boss and trough are sopositioned that the rotor is stopped in closed circuit position and inthe desired open circuit position, and undue oscillations or strainingof the rotor spring 33 do not occur.

A circuit breaker constructed in accordance with the invention may beconstructed in small and compact form, and may then be easily mountedwhere limited space is available. In fact, because of the size of suchsmall circuit breakers a number of such circuit breakers may be mountedside by side on a panel board and may be operated simultaneously by handwith ease and convenience. Furthermore, the bi-metal overload trippermits use of the circuit breaker with either A. C. or D. 0. Stillfurther, such circuit breakers are sturdy and maybe used for a varietyof purposes and may be constructed in a variety of sizes. Finally,minimum force is required to trip or reset this circuit breaker.

The particular form of the invention here described and illustrated inthe accompanying drawings is presented merely as an example of how theinvention may be applied. Other forms, embodiments and applications ofthe invention, coming within the proper scope of the appended claims,will readily suggest themselves to those skilled in the circuit breakerart.

I claim:

1. In a circuit breaker, a fixed contact, a pivotally mounted movablecontact for engaging said fixed contact, means for normally urging saidmovable contact into open circuit position, releasable means for holdingsaid movable contact in circuit closing position, a, separately pivotedmanually operable member unconnected with the mounting of said movablecontact for moving said movable contact into circuit closing position,and means for releasing said releasable means.

2. In a circuit breaker, a fixed contact, a pivotally mounted movablecontact for engaging said fixed contact, means for normally urging saidmovable contact into open circuit position, releasable means for holdingsaid movable contact in circuit closing position, a separately pivotedmanually operable lever unconnected with the mounting of said movablecontact movable in one direction to move said movable contact intocircuit closing position and movable in the opposite direction torelease said releasable means, and heat responsive means for releasingsaid releasable means.

3. In a circuit breaker, a fixed contact, a pivotally mounted movablecontact for engaging said fixed contact, a spring for normally urgingsaid movable contact into open circuit position, a second spring forholding said movable contact in circuit" closing position, a, separatelypivoted manually operable lever unconnected with the mounting of saidmovable contact for moving said movable contact into circuit closing andopen circuit position, and a bi-metal element in circuit with saidmovable contact for releasing said second spring and thereby releasingsaid movable contact from circuit closing position.

4. In a circuit breaker, a casing, a contact fixed in said casing, arotor pivoted in said casing, a roller eccentrically pivoted to saidrotor, a second contact fixed to said rotor adapted to engage said fixedcontact, and a manually operable lever separately pivoted in said casingfor moving said rotor into circuit closing position, a face of saidlever being positioned to contact said roller for so moving said rotor.

5. A circuit breaker comprising a casing, a contact fixed in saidcasing, a rotor pivotedin said casing, a second contact fixed to saidrotor adapted to engage said fixed contact, means for normally urgingsaid rotor into open circuit position, releasable means for holding saidrotor in circuit closing position, a manually operable member separatelypivoted in said casing and unconnected with the mounting of said rotorfor moving said rotor into circuit closing position, and means forreleasing said releasable means.

6. A circuit breaker comprising a casing, a contact fixed in saidcasing, a rotor pivoted in said casing, a second contact fixed to saidrotor adapted to engage said fixed contact, means for normally urgingsaid rotor into open circuit position, releasable means for holding saidrotor in circuit closing position, a manually operable member separatelypivoted in said casing and unconnected with the mounting of said rotorfor moving said rotor into circuit closing position, and bi-metal meansfor releasing said releasable means.

'7. A circuit breaker comprising a casing, a contact fixed in saidcasing, a rotor pivoted in said casing, a second contact fixed to saidrotor adapted to engage said fixed contact, means for normally urgingsaid rotor into open circuit posi- 8. A circuit breaker comprising acasing, a contact fixed in said casing, a rotor pivoted in said casing,a second contact fixed to said rotor adapted to engage said fixedcontact, means for normally urging said rotor into open circuitposition, releasable means for holding said rotor in circuit closingposition, heat-responsive means for releasing said releasable means, anda manually operable member separately pivoted in said casing movable inone direction to move said rotor into circuit closing position andmovable in the opposite direction to release said releasable means.

9. A circuit breaker comprising a casing, a contact fixed in saidcasing, a rotor pivoted in said casing, a second contact fixed to saidrotor adapted to engage said fixed contact, a spring for normally urgingsaid rotor into open circuit position, a second spring for releasablyholding said rotor in circuit closing position, a heatresponsive metalstrip for releasing said second spring, and a manually operable memberseparately pivoted in said casing movable in one direction to move saidrotor into circuit closing position and movable in the oppositedirection to release said second spring.

10. A circuit breaker comprising a casing formed of insulating material,a contact fixed in said casing, a rotor formed of insulating materialpivoted in said casing, a second contact fixed to said rotor adapted toengage said fixed contact, a spring for normally urging said rotor intoopen circuit position, a second spring for releasably holding said rotorin circuit closing position, a bi-metal element included in the circuitwhen said circuit is closed for releasing said second spring, and amanually operable lever formed of insulating material separately pivotedin said casing movable in one direction to turn said rotor into circuitclosing position and movable in the opposite direction to release saidsecond spring, substantially as described.

HALL LANGSTROTH.

